rpc 패키지 추가

rpc/rpc.go

@@ -0,0 +1,190 @@
+package rpc
+
+import (
+	"bytes"
+	"context"
+	"encoding/gob"
+	"errors"
+	"fmt"
+	"reflect"
+	"runtime"
+	"strings"
+	"time"
+
+	"github.com/go-redis/redis/v8"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+	"repositories.action2quare.com/ayo/gocommon/logger"
+)
+
+type Receiver interface {
+	TargetExists(primitive.ObjectID) bool
+}
+
+type receiverManifest struct {
+	r       Receiver
+	methods map[string]reflect.Method
+}
+
+type rpcEngine struct {
+	receivers map[string]receiverManifest
+	publish   func([]byte) error
+}
+
+var engine = rpcEngine{
+	receivers: make(map[string]receiverManifest),
+}
+
+func RegistReceiver(ptr Receiver) {
+	rname := reflect.TypeOf(ptr).Elem().Name()
+	rname = fmt.Sprintf("(*%s)", rname)
+
+	methods := make(map[string]reflect.Method)
+	for i := 0; i < reflect.TypeOf(ptr).NumMethod(); i++ {
+		method := reflect.TypeOf(ptr).Method(i)
+		methods[method.Name] = method
+	}
+	engine.receivers[rname] = receiverManifest{
+		r:       ptr,
+		methods: methods,
+	}
+}
+
+func Start(ctx context.Context, redisClient *redis.Client) {
+	if engine.publish != nil {
+		return
+	}
+
+	pubsubName := primitive.NewObjectID().Hex()[6:]
+	engine.publish = func(s []byte) error {
+		_, err := redisClient.Publish(ctx, pubsubName, s).Result()
+		return err
+	}
+
+	go engine.loop(ctx, redisClient, pubsubName)
+}
+
+func (re *rpcEngine) callFromMessage(msg *redis.Message) {
+	defer func() {
+		r := recover()
+		if r != nil {
+			logger.Error(r)
+		}
+	}()
+
+	encoded := []byte(msg.Payload)
+	var target primitive.ObjectID
+	copy(target[:], encoded[:12])
+
+	encoded = encoded[12:]
+	for i, c := range encoded {
+		if c == ')' {
+			if manifest, ok := re.receivers[string(encoded[:i+1])]; ok {
+				// 리시버 찾음
+				if manifest.r.TargetExists(target) {
+					// 이 리시버가 타겟을 가지고 있음
+					encoded = encoded[i+1:]
+					decoder := gob.NewDecoder(bytes.NewBuffer(encoded))
+					var params []any
+					if decoder.Decode(&params) == nil {
+						method := manifest.methods[params[0].(string)]
+						args := []reflect.Value{
+							reflect.ValueOf(manifest.r),
+						}
+						for _, arg := range params[1:] {
+							args = append(args, reflect.ValueOf(arg))
+						}
+						method.Func.Call(args)
+					}
+				}
+			}
+		}
+	}
+}
+
+func (re *rpcEngine) loop(ctx context.Context, redisClient *redis.Client, chanName string) {
+	defer func() {
+		r := recover()
+		if r != nil {
+			logger.Error(r)
+		}
+	}()
+
+	pubsub := redisClient.Subscribe(ctx, chanName)
+	for {
+		if ctx.Err() != nil {
+			return
+		}
+
+		if pubsub == nil {
+			pubsub = redisClient.Subscribe(ctx, chanName)
+		}
+
+		msg, err := pubsub.ReceiveMessage(ctx)
+
+		if err != nil {
+			if err == redis.ErrClosed {
+				time.Sleep(time.Second)
+			}
+			pubsub = nil
+		} else {
+			re.callFromMessage(msg)
+		}
+	}
+}
+
+var errNoReceiver = errors.New("no receiver")
+
+type RpcCallContext struct {
+	r Receiver
+	t primitive.ObjectID
+}
+
+var ErrCanExecuteHere = errors.New("go ahead")
+
+func MakeCallContext(r Receiver) RpcCallContext       { return RpcCallContext{r: r} }
+func (c *RpcCallContext) Target(t primitive.ObjectID) { c.t = t }
+func (c *RpcCallContext) Call(args ...any) error {
+	if c.r.TargetExists(c.t) {
+		// 여기 있네?
+		return ErrCanExecuteHere
+	}
+
+	pc := make([]uintptr, 1)
+	n := runtime.Callers(2, pc[:])
+	if n < 1 {
+		return errNoReceiver
+	}
+
+	frame, _ := runtime.CallersFrames(pc).Next()
+	prf := strings.Split(frame.Function, ".")
+	rname := prf[1]
+	funcname := prf[2]
+
+	serialized, err := encode(c.t, rname, funcname, args...)
+	if err != nil {
+		return err
+	}
+
+	return engine.publish(serialized)
+}
+
+func encode(target primitive.ObjectID, receiver string, funcname string, args ...any) ([]byte, error) {
+	buff := new(bytes.Buffer)
+
+	// 타겟을 가장 먼저 기록
+	buff.Write(target[:])
+
+	// receiver
+	buff.Write([]byte(receiver))
+
+	// 다음 call context 기록
+	m := append([]any{funcname}, args...)
+	encoder := gob.NewEncoder(buff)
+	err := encoder.Encode(m)
+	if err != nil {
+		logger.Error("rpcCallContext.send err :", err)
+		return nil, err
+	}
+
+	return buff.Bytes(), nil
+}